Many electrical devices rely on batteries as a power source. While having certain drawbacks, the batteries allow the electrical devices to be highly portable. These battery powered devices may be operated where no convenient source of power may be found, or it may be operated free from any encumbering extension cords. Common disposable batteries include, for example, alkaline batteries. One of the significant drawbacks of battery powered devices is the expense of disposable batteries. This drawback has been overcome with the introduction of a variety of rechargeable batteries. Some of the more common rechargeable batteries include nickel cadmium batteries (NiCads), sealed lead-acid batteries and gel type batteries. Recently, manufactures have made use of more exotic technologies, such as nickel hydride and lithium ion, to produce rechargeable batteries having enhanced performance characteristics.
A unitary battery recharger is used to charge spent or drained rechargable batteries. The user removes the drained rechargeable batteries from the electrical device and places the batteries into the battery recharger. The battery recharger often includes a housing, an adapter and an electrical cord connecting the housing and the adapter. The housing may have a number of electrical contacts for holding and forming electrical connections with batteries of various sizes. The adapter includes a set of electrical prongs designed to be accepted in standard electrical outlets, such a the common wall-mounted outlets found in most buildings. The adapter will typically contain all of the circuitry necessary for converting an alternating current (AC), such as the 110 V AC current commonly found in the United States, to an appropriate direct current (DC) for recharging the spent batteries. The battery recharger may contain additional circuitry for controlling the flow of current to the battery, for example, reducing or terminating current flow if the temperature of the battery exceeds a safe operating temperature.
Rechargeable power packs are becoming increasingly common. The power packs often contain multiple battery cells and electrical circuitry that, for example, may indicate a power status for the power pack. The power pack may be easily loaded into an electrical device, and is more convenient than handling multiple batteries. The power packs are recharged in a similar manner to the rechargeable batteries, the spent power pack being inserted into a power pack recharger. Power is typically supplied from a standard wall-mounted outlet, by way of an adapter, similar to the adapter of the battery recharger. The recharger may contain additional electrical circuitry, such as circuitry for controlling the recharging operation.
Current power packs and their recharging systems have a number of disadvantages. A user must gain access to a recharger each time the battery or power pack requires recharging. It may be inconvenient to retrieve the recharger or the recharger may often be misplaced. Consequently, large amounts of time may be lost retrieving or searching for the recharger. Also, rechargers are bulky. When working off site, the bulky recharger must be taken along to recharge the power pack.